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Abstract :

The aim of the PhD thesis was to assess the effectiveness of a promising original disinfectant product to decrease the prevalence of digital dermatitis (DD) in dairy herds. This product should be acceptable for farmers, not toxic both for human and the environment and finally allow a rational use of antibiotics. A first part consisted in a meta-analysis of the existing literature about the effectiveness of collective treatments on the healing and prevention of DD lesions. This metaanalysis, besides revealing weak evidence for supporting collective treatment, allowed us to highlight the drawbacks to avoid for our further clinical trial. In a second step, prior to the clinical trial, we assessed both in vitro and in vivo the impact of organic matter and slurry on the efficacy of the disinfectant. This step, rarely conducted for other products, led to determine the most appropriate renewal rate for the footbath under field conditions. A third and last part was devoted to a clinical trial, under good clinical practices, to assess both healing and preventive effect of different regimes of the new disinfectant in comparison to a placebo group, using a split footbath allowing to treat one side of the cow, this latter being, therefore, its own control. The effectiveness was assessed through (i) the evolution over time of DD lesions using survival analysis and (ii) through the description over time of the microbiota found in feet skin biopsies performed before and after treatment using 16s rRNA analysis. The results reported mainly a healing effect of the disinfectant and confirmed the need for a global approach including other risk factors such as hygiene and concomitant individual treatments, to control this multifactorial disease

Key words :

Dairy cow, Digital dermatitis, Epidemiology, Meta-analysis, Clinical trial, Microbiota